1. Field of the Invention
This invention relates to apparatus for reproducing signals from a record medium and, more particularly, to such apparatus which is capable of reproducing either digital or analog audio signals that are recorded on, for example, magnetic tape.
2. Description of the Prior Art
Conventional analog audio tape recorders are known wherein an analog signal is recorded in a longitudinal track on a magnetic tape driven past a stationary head that reproduces the analog signal. In conventional high fidelity audio equipment, two channels of audio signals normally are recorded to provide left (L) and right (R) stereophonic channels of audio information. Typically, the magnetic tape is housed in a cassette, such as the conventional compact cassette, wherein the tape may be driven first in one direction to reproduce one audio program comprised of left and right channels of audio information recorded on one "side" of the tape, and then in the opposite direction to reproduce another program of left and right channels of audio information recorded on the other "side".
In some cassette players operable with such cassettes, the two different directions of movement of magnetic tape are achieved simply by turning the cassette over to play a "different side" of the tape. Other cassette players include a so-called "auto-reverse" feature, whereby the tape is driven in one direction to reproduce signals from one "side" and then, when the tape reaches its end, or upon selection by the user, the tape transport direction is reversed such that signals recorded on the other "side" are played back. In actuality, the two "sides" of the tape comprise upper and lower longitudinal halves of one tape surface, the two halves respectively lying above and below the center line of the tape. Digital audio tape players also are known in which audio signals are recorded in digital form in separate longitudinal tracks, or channels of the tape. Recording or reproduction of these digital signals is achieved by using an individual head for each channel, whereby plural channels are recorded or reproduced substantially simultaneously. Like the analog audio cassette player, the digital audio cassette player, is capable of reproducing digital signals recorded in longitudinal tracks on two "sides" of the tape, i.e. in tracks on upper and lower halves of the tape.
In one type of digital tape player the tape must be turned over to permit the digital signals recorded on each "side" of the tape to be played back. In other digital tape players having the aforementioned "auto reverse" feature, the direction of movement of the tape merely is reversed to permit digital signals recorded on each "side" to be reproduced.
In both analog and digital tape players having the "auto reverse" feature, two sets of heads normally are provided: one set to reproduce analog or digital signals (as the case may be) from one half portion of the tape (e.g. from "side" A) when the tape is driven in the forward direction and another set of heads to reproduce analog or audio signals from the other half portion of the tape (e.g. from "side" B) when the tape is reversed. Of course, for analog and digital tape players that do not exhibit the "auto reverse" capability, only one set of heads need be provided.
Although separate analog audio signal reproducing apparatus and digital signal reproducing apparatus are known, it often is desirable to provide both analog and digital reproducing capabilities in a single machine. It had been thought that such dual analog and digital capability requires separate transducers (i.e. separate analog and digital heads) as well as separate and independently operable signal processing circuitry. Of course, the use of separate sets of heads and separate processing circuits is expensive, occupies substantial space, results in bulky equipment, and is complicated to assemble and use.